The Protein Core facility is one of the research cores in the Rheumatic Diseases Core Center (RDCC) at Washington University. It proposes the following Specific Aims to sustain and develop new state-of-the-art protein services to RDCC members: 1) Support continued progress and growth of the Hybridoma Center; and 2) Support continued progress and growth of the Protein Production and Purification Facility. The Hybridoma Center aids RDCC investigators in the generation of primary hybridomas secreting monoclonal antibodies that are critical to contemporary immunology and rheumatic diseases research. New services are being tested to offer RDCC investigators rabbit monoclonal antibodies and genetic immunization, for example. The Protein Production and Purification Facility aids RDCC investigators by producing and purifying large quantities of monoclonal antibodies for their studies. In addition, it has recently gained expertise in producing and purifying recombinant and native proteins from a number of different expression systems. This service will now be made available to the RDCC community.